US3791515A

US3791515A - Document sorting and handling machines

Info

Publication number: US3791515A
Application number: US00303941A
Authority: US
Inventors: D Wood
Original assignee: Masson Scott Thrissell Engineering Ltd
Current assignee: Masson Scott Thrissell Engineering Ltd
Priority date: 1972-11-06
Filing date: 1972-11-06
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

A conveyor for carrying documents or envelopes comprising an endless flexible belt provided with spaced carriers in the form of metal rods with multiple bends moving along ribbed or grooved supporting surfaces, the belts being also formed with spaced teeth to engage toothed driving sprockets, so that the positions of the conveyed articles are accurately determined. Below the supporting surface sorting boxes are located each with a diverter gate movable into the path of the travelling articles, and a number of such conveyors are positioned end-to-end to transfer mail from one to the next.

Description

United States Patent 7 [191,

Wood

[ l- DOCUMENT SORTING AND HANDLING MACHINES [75] Inventor: David Wood, Clevedon, England 1 [73] Assignee: Masson Scott Thrissell Engineering Limited, Bristol, England [22] Filed: Nov. 6, 1972 21 Appl. No.: 303,941

111 3,791,515 i451 Feb. 12,1974

Primary Examiner-Richard A. Schacher Attorney, Agent, or Firm-Young & Thompson [57] ABSTRACT A conveyor for carrying documents or envelopes comprising an endless flexible belt provided with spaced carriers in the form of metal rods with multiple bends [52] US. Cl 209/73, 209/74 R, 209/DIG. l l b d f 51 Im. Cl. 1307c 3/06 a ed suppmtng [5 8] FieldofSearch...209/73,DIG. 1,74 R; 198/174, the belts fmmed Spaced lf" 7 {95,738 gage toothed driving sprockets, so that the positions of the conveyed articles are accurately determined. 7 Below the supporting surface sorting boxes are located [56] References Cited each with a diverter gate movable into the path of the, UNITED STATES PATENTS travelling articles, and a number of such conveyors are 2,937,739 5/1960 Levy 198/38 positioned end-to-end to transfer mail from ne to the 3,162,259 12/1964 Burroughs. next 3,674,143 7/1972 Hunter 209/74 R I FOREIGN PATENTS OR APPLICATIONS 6 Claims, 6-Drawing Figures 1,096,289 12/1960 Germany 209/010. 1

e? (0 Q1 K 13 2 tail -2 P a 72 PATENIED FEB 1 21914 DOCUMENT SORTING AND HANDLING MACHINES This invention relates to machines for handling and- /or sorting documents or other articles such as mail envelopes, or the like.

The invention is concerned particularly but not exclusively with sorting machines of the type comprising an input or identifying unit where the articles (hereinafter referred to for convenience as envelopes) are inspected visually or by machine, and decoded, or otherwise identified as to their sorting addresses, and a sorting unit in which the envelopes are carried by a conveyor system past a number of diverters which are operated automatically and selectively by the input unit to divert selected envelopes to sorting stations or positions.

Existing machines of this type commonly comprise endless belt-type conveyors, sometimes combined with roller conveyors, arranged to convey the envelopeseither individually ,or in presorted boxes or containers over preselected paths so as to pass a succession of solenoid operated diverter gates which are actuated at the appropriate time instants properly related to the travel and speed of the envelopes, so that a selected diverter gate will open at .the correct instant when the respective envelope is about to reach that gate. Such machines suffer from inaccurate timing errors caused by stretch of the belts, which may run the whole length of themachine, so that the cumulative error at the far end of a belt can be quite appreciable. Moreover with conventional belt conveyors the envelopes are not positively located in relation to the belt, and therefore it is necessary to have greater pitch or interval between letters to offset the inaccuracy of the positional control. Moreover the slip, or relative movement or positional error of the envelopes can only be compensated by increasing the pitch or distance between envelopes, which in turn increases the necessary transport speed for any given sorting rate per hour.

Other types of conveyors sometimes used with sorting machines of this general type consist of a series of pairs of rollers arranged to nip and drive the envelopes from one to the next, with one roller of each pair driven by suitable gearing, belt or chain drives, or otherwise. Driven roller conveyors of this type suffer from many of the disadvantages of belt conveyors and in addition they are noisy and involve considerable friction owing to the large numbers of rollers and bearings, the letters are not positively and accurately driven and located, lubrication presents a problem, and the drive means between the rollers may produce the equivalent of stretch or lag, resulting in further positional errors. I

Accordingly it is one object of the invention to provide an improved sorting machine with a conveying system which will eliminate or at least reduce some of the problems and disadvantages of existing methods.

' It is a further object of the invention to provide an improved conveying system, especially for a document sorting machine, which will handle and present the envelopes or documents in such a way that some of the disadvantages of existing systems are avoided. Thus in one existing type of document handling machine the documents are conveyed along the length of a conveyor lying flat on the conveyor belt or track and with their longer lengths parallel with the direction of movemerit. To obtain any substantial performance in terms of documents per hour the linear speed of the documents must be very great in such a system. This introduces problems in accurately locating and positioning the envelopes, introducing them correctly into the conveyor, and operating the diverter gates. Moreover for any practical machine the dimensions tend to be increased undesirably.

in another existing type'of machine the documents or envelopes are conveyed individually or in groups lying in planes perpendicular to the direction of movement of the conveyor. For example the envelopes may be in vertical attitudes on a horizontal moving conveyor and extending across the width of the conveyor belt. In such systems the linear speed of travel can be considerably reduced for any given sorting rate but problems arise in introducing and removing envelopes when closely stackedlin such a system.

Accordingly from one aspect the invention consists broadly in a transporting system for conveying individual mail items or documents, or packages thereof, in a sorting machine, including an endlessbelt formed with regularly spaced teeth or locating elements acting as driving and indexing elements, and provided with further regularly spaced carrier or pusher members for engaging and conveying the articles to be sorted.

In a preferred construction .the carrier members are formed with spaced fingers, loops, or other pusher members, to engage an edge of an article to be sorted,

and to fit partly into or between a cooperating ridged or grooved surface or group of rails for supporting the article.

From another aspect the invention consists in a sorting apparatus, for articles of mail, documents, or the like, including a number of modular units, each including a number of sorting positions at different levels, conveyor systems for moving the articles through the respective unit at each level, and deflector gates for defleeting articles into selected positions, the modular units being designed and arranged to be coupled together in varying numbers to form sorting equipment of varying capability.

From yet another aspect the invention consists in a sorting machine or system, including a conveyor for movingitems, packages, or containers of mail items, documents or the like, consisting of a number of sepa rate endless belt or chain conveyor sections, each driven at one end by a common transmission system, such that stretch or lag in the conveyor sections is not cumulative.

From yet another aspect the invention consists in a sorting machine for mail items, documents or the like, including a feeding device and a conveyor system arranged to transport the articles-lying flat in planes parallel with the plane of the conveyor and with the major dimension of the article extending transversely across the conveyor. l

The invention may be performed in various ways and one particular embodiment, with some possible modifications, will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevation illustratingthe main components of a letter sorting machine to which the invention may be applied,

FIG. 2 is a diagrammatic plan view on an enlarged scale showing a series of conveyor belt sections of the machine of FIG. 1, arranged end-to-end to form an extended conveyor,

FIG. 3 is a side elevation on a somewhat enlarged scale showing in more detail the construction of the transfer device for moving documents between adjacent conveyor sections,

FIG. 4 is a diagrammatic end view on an enlarged scale, and partly in section, showing a portion of one of the comb type pushers carried by the conveyor belts,

FIG. 5 is a diagrammatic side elevation illustrating a fault detection system incorporated in the conveyor,

and

FIG. 6 is a diagrammatic view, corresponding to part of FIG. 5, on a further enlarged scale, the operation of the detection system of FIG. 5.

Referring first to FIG. 1 the machine consists essentially of an input section 9 combined with a conveying and sorting section consisting of a series of sorting modules. In this illustrated example there are only two modules 10 and 11, but any desired number may be provided, and further modules can be added without difficulty to an existing system. The input section 9 may be of generally conventional design and construction, and may include an automatic letter facing unit (not shown) followed by a manual or automatic coder or decoder .16. In a manual system the envelopes are presented in succession before an operator at a key board who types appropriate code symbols onto the envelope, in a form in which they can subsequently be read by an automatic reader such as 16. In the alternative automatic system as illustrated the envelopes carry preprinted code symbols and are fed by a stepping conveyor direct to the automatic reader 16. From the reader 16 the envelopes are automatically fed in succession into a belt conveyor 8 which transfers them to a vertical conveyor 19, from which they are selectively diverted by solenoid-operated diverter gates 18 into any selected one of (say) 4 levels. At each level a further conveyor system 13 is arranged to convey the envelopes horizontally away from the-starting point, and in doing so the letters pass a series of diverter gates 14 which control the selective delivery of letters into the individual sorting boxes 12. The gates 14 and l8 are controlled in known manner by the automatic reader .16. The conveyor systems 13 are of the positivepositional type, with positive carrier members at fixed intervals along the conveyors. The conveyor 8, particularly if of any great length, may also be of the positivepositional type.

In normal existing sorting machines of this general type the conveyor belts extend horizontally the full length of the machine and are liable to a considerable degree of stretch, whichcan cause inaccuracies in the speed and location of envelopes and consequent incorrect sorting.

'In this example of the invention the problem of stretch in the horizontal conveyor belts 13 is avoided by building up these conveyors from a number of shorter sections, as illustrated more clearly in FIGS. 2 and 3. Each conveyor section 13 extends for the length of one of the modules l0, 11, etc., and each comprises a pair of parallel

flexible belts

20, 21, formed with teeth 22 on one side to permit the belt to be driven and accurately indexed relative to a toothed driving sprocket 23 at one end. The sprocket 24 at the other end is not driven, but the sprocket bearing is resiliently sprung away from the first sprocket to hold the

belts

20, 21, taut. The other (external) surface of each belt is provided with a series of spaced pusher elements (indicated at 25 in FIG. 3) to engage and transport the individual envelopes, and details of one preferred pusher element are described in more detail below with reference to FIG. 4. 1

As shown in FIG. 2 the driving sprocket 23 of each belt section 13 is driven through a multiple driving chain system comprising a series of chain loops 26, positively interconnecting the shafts of the sprockets 23, so that all rotate in synchronism. Alternatively the sprockets 23 may be driven through a suitable gearing from a continuous longitudinal driving shaft, preferably so designed and arranged that there is little if any lag or stretch between one end of the machine and the other. As a result if there should be any slight stretch in an individual belt length the out-of-phase error will be corrected or restored at the next belt section so that the overall or cumulative error is accordingly reduced, particularly at the last section.

FIG. 3 illustrates the preferred system for transferring documents between different modules 10, 1 1, etc., and designed to maintain the accurate timing or positioning of the letters as they proceed from one module to the next. Each letter is slightly accelerated at the moment of transfer to avoid any undesirable interactionv between the edges of the letter and the adjacent pusher elements 25 on the adjacent sections of conveyor belt.

For this purpose the shaft of the sprockets 24 on the downstream side of the module junction has three drums 30 symmetrically spaced across the width of the conveyor. The diameter of each drum 30 is such that its peripheral speed is slightly greater than the conveyor speed, and each drum is provided at one part of its surface with a recess (not illustrated) to allow the pushing elements 25 to pass freely around the drive pulley or sprocket. Vertically below each drum is a pressure roll 31 resiliently sprung upwards and cooperating with a pre-set stop to provide a minimal gap slightly less than the normal thickness of a letter. Thus three driving nips are formed between the drums 30 and rolls 31, capable of driving the letter 33 through the transfer stage even without the assistance of one of the pusher elements 25. The pre-set roller gap or nip assists in obtaining a positive pick-up and prevents the pressure rolls 31 from entering the slots in the drums. At the point of transfer the normal drive to the letter is lost, but the acceleration of the letter also serves the useful purpose of advancing the letter during this instant.

After the letter has been ejected from the nip into the next conveyor section (i.e., to the left in FIG. 3) it is-slowed down by friction until the following pusher bar 25 regains control immediately after, and accurate timing is completely restored. A projecting platform or rail from one module lines up with the bed or static conveyor platform of the adjacent module so that the letters can travel horizontally without interruption from one module to the next.

The preferred pusher bar system is illustrated in FIG. 4. The moving conveyor belt cooperates with a static supporting system or dead plate 40 formed with a number of longitudinally extending spaced ribs or rails 41, interrupted as necessary along the length of the machine to permit the letters 33 to be diverted downwards into the sorting boxes or cassettes 12 by the diverter gates 14 which are positioned in line with these rails 41 across the width of the conveyor. Cooperating with the rails 41 of the dead plate 40 are a series of elongated spaced top guides or rails 43 carried by overhead supports 44 and providing sufficient clearance from the dead plate for the individual letters 33 and pusher bars to travel along the length of each module 10, 11, as

, necessary.

Each pusher bar 25 is an undulating metal rod, pivotally mounted at each end in a support pad or bearing 47 carried by one of the two operating

belts

20, 21 of the conveyor, one on each side. The pusher rods 25 are spaced apart along the length of the belt at predetermined intervals, related to the standard size of the envelopes and to the intervals of the teeth 22 on the belt. In the example illustrated in FIG. 4 the undulating rod 25 has lower depending loops 48 which lie respectively between one of the top guides 43 and the dead plate and intervening upward loops 49 which provide gaps or clearances where the tips of the diverter gates are raised above the level of the envelopes. Each diverter gate 14 may for example comprise five parallel fingers 50 arranged to rock together about a horizontal axis, and spaced across the width of the conveyor to engage across the whole length of the edge of an envelope. The undulating pusher bar 25 has a corresponding number of loops 49 to accommodate these diverter fingers.

In this particular system the letters are arranged to be conveyed individually, each lying horizontally flat on the conveying surface with its larger dimension or length across the conveyor. This has several advantages compared with more normal systems in which the letters are conveyed in other attitudes. If the individual letters lie horizontally flat on the conveyor surface with their larger length parallel to the direction of movement the speed of the conveyor must be increased to achieve any specific sorting rate or the sorting rate must be reduced. Also the overall length of the machine must be undesirably increased. If alternatively the letters are conveyed in vertical attitudes, i.e., the parallel vertical planes, the dimensions and speed of the conveyor can be reduced for any specific sorting rate, but other problems arise in transporting and diverting envelopes to and from the conveyor.

Each undulating bar 25 is torsionally sprung in its pivot mounting, against a limit stop, such that its normal position is in a generally vertical plane as shown in FIG. 4. In the event of a fault or jam in the conveyor, the increased resistance to the movement of the bar 25 will cause it to rotate in its bearing pads 47, and so cause pivotal movement of a metal blade 52 attached to the end of each bar 25. The blades 52 act as optical shutters" or interposers in an optical fault detection system illustrated in FIGS. 5 and 6.

When any of the pusher bars .25 is rotated the interposer blade 52 moves downwards as indicated at 54 in FIG. 5, into the path of an optical beam 55 projected horizontally below and to one side of the dead plate 40 by a light projector 57. The beam is directed along the length of the conveyor to a photo-cell optical receiver 58 at the other end, and it will be seen that if any one of a number of interposer blades 52 moves downwards to intercept the light beam the system will indicate a failure. The optical receiver 58 is connected to suitable electric circuitry for providing a visible or audible warning and for immediately interrupting the drive to the conveyor.

FIG. 6 illustrates geometrically the movement of the interposer blades 52 as they pass around the right-hand end sprockets 24 of one of the conveyor sections, and this illustrates the factors governing the choice of various dimensions and relationships such as the vertical position of theoptical beam. It will be noted that although each of the interposer blades 52 may remain in its normal undeflected attitude throughout its move ment, during the lower part of its rotational movement at the extremity of the conveyor section, the locus or path 60 of the extreme tip 61 of the blade will drop to a level 63 appreciably below the normal level 62 of the blade during the horizontal run. In this angular travel the interposer blade 52 will interfere with any optical beam positioned within the vertical range D in FIG. 6. For the optical system to operate as a detection unit therefore it is necessary to ensure that any rotation of a pusher bar 25, which requires a fault detection output signal, will move the prospective interposer blade 52 below this vertical range D into the region t where the beam 55 is located. This can be achieved either by slightly increasing the length of the interposer blade or by increasing the operating angle 6 through which the blade will rotate. Unfortunately increase in the interposer blade length gives an increased radius of the locus of the blade tip 61 and so further increases the interference sector, so that the position of the optical beam must be lowered even further. In fact it can be shown that there is an optimum length for the interposer blade to give the minimum operating angle 0, which can be calculated mathematically.

The sensitivity of the system is preferably high enough to allow detection of a thin letter trapped beneath a pusher bar as shown at 65 in the right hand part of FIG. 5. A particular advantage of the 'system is that maximum sensitivity occurs at the point of maximum interference as shown at 66 in FIG. 6. It is at this point where faults, if any, are most likely to occur, as a mistimed letter entering the conveyor would deflect the pusher bar 25 at approximately this point. Therefore thequickest and most effective response is obtained at this more critical part of the machine cycle.

In a possible alternative systemmeans may be pro vided for inhibiting or otherwise rendering inoperative the

optical detection system

57, 58, during the interference period of each of the interposer blades 52. This can be achieved electrically by applying suitable electronic gating logic to the electrical output circuit associated with the optical receiver.

I claim:

1. Sorting apparatus, for sorting articles of mail, doc--.

uments, or the like, comprising a plurality of separate modular units arranged horizontally in alignment and operatively interconnected to provide an integrated sorting system, each said modular unit comprising a row of sorting positions, each having a receptacle for sorted articles and an automatically controlled deflector gate for deflecting articles into said receptacle, and conveying means for transporting unsorted articles along said row of sorting positions to be selectively engaged by one of said deflector gates, said conveying means comprising an elongated stationary support element above said sorting receptacles, a moving conveyor including an endless flexible conveyor member provided with regularly spaced driving and indexing teeth, and further provided with regularly spaced pusher members to engage said articles at accurately determined intervals and to convey said articles along said stationary support element over said sorting receptacles, and drive means for said moving conveyor including a toothed rotary drive member engaging said indexing teeth on said conveyor member, and wherein said conveying means of two adjacent modular units are located end-to-end in close proximity to convey unsorted articles directly from one modular unit to the next, and said sorting apparatus includes synchronised positive drive means operatively coupled to said toothed drive members of said two adjacent modular units, to maintain a predetermined spacial relationship between said pusher members of said two modular units.

2. Sorting apparatus according to claim 1, wherein said stationary support element of one modular unit extends substantially continuously and in alignment with the stationary support element of the next adjacent modular unit, and including means for temporarily accelerating each article at the instant of transfer from one modular unit to the next.

3. Sorting apparatus according to claim 2, wherein said accelerating means comprise a pair of cooperating rollers, one of said rollers being driven by drive means coupled to the toothed rotary drive member of one of said modular units, and wherein said cooperating rollers grip and propell and article being sorted into contact with one of said pusher members of the conveyor means of the next adjacent modular unit.

4. Sorting apparatus according to claim 1, wherein each of said pusher members is pivotally connected to the respective flexible conveyor member, and including biassing means urging each pusher member towards an operative pivotal position for engaging an article to be sorted.

5. Sorting apparatus according to claim 1, wherein said synchronised positive drive means includes a positive transmission element extending longitudinally parallel with said moving conveyors of two adjacent modular units, and operatively connected to the toothed rotary drive members of said two moving conveyors.

6. Sorting apparatus according to claim 1, wherein each of said flexible conveyor members comprises an endless flexible toothed belt.

Claims

1. Sorting apparatus, for sorting articles of mail, documents, or the like, comprising a plurality of separate modular units arranged horizontally in alignment and operatively interconnected to provide an integrated sorting system, each said modular unit comprising a row of sorting positions, each having a receptacle for sorted articles and an automatically controlled deflector gate for deflecting articles into said receptacle, and conveying means for transporting unsorted articles along said row of sorting positions to be selectively engaged by one of said deflector gates, said conveying means comprising an elongated stationary support element above said sorting receptacles, a moving conveyor including an endless flexible conveyor member provided with regularly spaced driving and indexing teeth, and further provided with regularly spaced pusher members to engage said articles at accurately determined intervals and to convey said articles along said stationary support element over said sorting receptacles, and drive means for said moving conveyor including a toothed rotary drive member engaging said indexing teeth on said conveyor member, and wherein said conveying means of two adjacent modular units are located end-to-end in close proximity to convey unsorted articles directly from one modular unit to the next, and said sorting apparatus includes synchronised positive drive means operatively coupled to said toothed drive members of said two adjacent modular units, to maintain a predetermined spacial relationship between said pusher members of said two modular units.